Impact of double heterozygosity for Factor V Leiden and Prothrombin G20210A on the thrombotic phenotype

INTRODUCTION

Because of the rarity of double heterozygosity for Factor V Leiden (FVL) and Prothrombin (FII) G20210A, little is known about the thrombotic phenotype in double heterozygotes.

MATERIAL AND METHODS

In a retrospective cohort study of patients referred for a thrombophilia work-up, we investigated whether double heterozygotes (n = 138) exhibit a more severe thrombotic phenotype compared with single FVL or FIIG20210A heterozygotes, single FVL homozygotes, or wildtype carriers.

RESULTS

The risk of venous thromboembolism (VTE) was higher for female but not male double heterozygotes compared with single heterozygotes (FVL: 2.51, 95%CI 1.55-4.08, FIIG20210A: 1.75, 95%CI 1.14-2.68) and wildtype carriers (HR 2.53, 95%CI 1.58-4.05) but not compared with FVL homozygotes (HR 1.31, 95%CI 0.94-1.83). Female double heterozygotes developed VTE nearly a decade earlier than wildtype carriers and FVL heterozygotes (mean 44.2 vs. 52.6 and 52.2 years), most often in association with oral contraceptives. Spontaneous VTE and arterial thromboembolic events were not more frequent in double heterozygotes compared with the other genotype groups. Deep vein thrombosis (DVT) of the lower limb was the predominant VTE location in double heterozygotes, atypical vein thrombosis was rare. A phenomenon that has been described as the FVL paradox, a higher proportion of isolated DVT than pulmonary embolism, was also found for double heterozygotes.

CONCLUSION

The thrombotic phenotype in double heterozygotes resembles the appearance of the thrombotic phenotype in FVL carriers but the thrombotic risk is aggravated by women-specific risk factors.

Many Mg-Mg bonds form the core of the Mg16Cp*8Br4K cluster anion: the key to a reassessment of the Grignard reagent (GR) formation process?

It caused a sensation eight years ago, when the first room temperature stable molecular compound with a Mg-Mg bond (LMgMgL, L = chelating ligand) containing magnesium in the oxidation state +1 was prepared. Here, we report the preparation of a [Mg16Cp*8Br4K]- cluster anion (Cp* = pentamethylcyclopentadiene) with 27 Mg-Mg bonds. It has been obtained through the reaction of KCp* with a metastable solution of MgBr in toluene. A highly-resolved Fourier transform mass spectrum (FT-MS) of this cluster anion, brought into vacuum by electrospraying its solution in THF, provides the title cluster's stoichiometry. This Mg16 cluster together with experiments on the metastable solution of MgBr show that: during the formation process of GRs (Grignard reagents) which are involved in most of sophisticated syntheses of organic products, not the highly reactive MgBr radical as often presumed, but instead the metalloid Mg16Cp*8Br4 cluster anion and its related cousins that are the operative intermediates along the pathway from Mg metal to GRs (e.g. Cp*MgBr).

UV photoexcitation of a dissolved metalloid Ge9 cluster compound and its extensive ultrafast response

Femtosecond pump-probe absorption spectroscopy in tetrahydrofuran solution has been used to investigate the dynamics of a metalloid cluster compound {Ge9[Si(SiMe3)3]3}(-). Upon UV photoexcitation, the transients in the near-infrared spectral region showed signatures reminiscent of excess electrons in THF (bound or quasi-free) whereas in the visible part excited state dynamics of the cluster complex dominates.

Analysis of prion protein aggregates in blood and brain from pre-clinical and clinical BSE cases

Prion diseases are infectious neurodegenerative diseases affecting humans and animals. The food-borne bovine spongiform encephalopathy (BSE) had serious impact on both economy and public health, respectively. To follow the pathogenesis of BSE, oral challenge studies were previously conducted, among others on the Isle of Riems, Germany (Balkema-Buschmann et al., 2011b). In the present work brain and plasma samples from this pathogenesis study were subjected to surface fluorescence distribution analysis (sFIDA). sFIDA is a diagnostic tool that exploits the aggregated state of the disease-related prion protein (PrP) as a biomarker for prion disorders. With the exception of one animal, all tested brain samples from clinical cattle exhibited a high titer of PrP particles. Moreover we could detect PrP aggregates already 16 and 24 months after infection. In contrast to our previous demonstration of PrP particles in blood plasma from scrapie sheep, however, no aggregates could be identified in plasma from pre-clinical and clinical cattle. This is in accordance with other studies suggesting a restriction of the BSE infection to the central nervous system.

Amyloid formation: age-related mechanism in Creutzfeldt-Jakob disease?

Protein aggregation occurs in many age-related neurodegenerative diseases, where it can lead to deposits of naturally occurring proteins in the brain. In case of Creutzfeldt-Jakob disease (CJD), these deposits consist of prion protein (PrP). CJD has three etiologies: spontaneous, genetic, or caused by infection. A polymorphism within the PrP gene is associated with susceptibility of infection. The main event in prion diseases is the conversion of PrP from its naturally occurring isoform to its disease-associated isoform. Here, we present the adaption of a previously reported in vitro conversion system based on hamster recombinant PrP to analyze amyloid fibril formation of human recombinant PrP. We further compare the aggregation characteristics of the human PrP according to the polymorphism variants M129 and V129.

A highly sensitive diagnostic assay for aggregate-related diseases, including prion diseases and Alzheimer's disease

Prion diseases, Alzheimer's disease, and Parkinson's disease are age-related neurodegenerative diseases that are characterized by the formation of protein aggregates during the progress of the disease. Although it is still not known whether these aggregates are causative for, or symptoms of, the disease. Many studies show that aggregates or even oligomers of the according proteins are neurotoxic and thus may lead to neurodegeneration. To understand disease-associated or causative mechanisms in respect to protein aggregation, an ultrasensitive tool to quantify these disease-related aggregates is required. In this study we introduce a specificity-enhanced version of surface-FIDA as an approach to count even single aggregates in tissue homogenate and body liquids.

Counting of single prion particles bound to a capture-antibody surface (surface-FIDA)

Hitherto accredited prion tests use the PK resistance of PrP(Sc), the pathogenic isoform of the prion protein, as a marker for the disease. Because of variations in the amount of disease-related aggregated PrP, which is not PK-resistant, these prion tests offer only limited sensitivity. Therefore, a prion detection method that does not rely on PK digestion would allow for the detection of both PK-resistant as well as PK-sensitive PrP(Sc). Furthermore, single particle counting is more sensitive than methods measuring an integrated signal. Our new test system is based on dual-colour fluorescence correlation spectroscopy (FCS). This method quantifies the number of protein aggregates that have been simultaneously labelled with two different antibodies using dual-colour fluorescence intensity distribution analysis (2D-FIDA). This only counts PrP aggregates, and not PrP monomers. To increase the sensitivity, PrP(Sc) was concentrated in a two-dimensional space by immobilizing it so that the antibodies could be captured on the surface of the slide (surface-FIDA). When the surface was systematically scanned, even single prion particles were detected. Using this new technique, the sensitivity to identify samples from scrapie-infected hamster as well as BSE-infected cattle can be dramatically increased in comparison with identification using FIDA in solution.

Monocytes from systemic lupus erythematous patients are severely altered in phenotype and lineage flexibility

OBJECTIVE

Cells of the myeloid lineage comprise a very heterogeneous population with many phenotypes and functional activities including macrophages and dendritic cells. To investigate the status, differentiative potential and lineage commitment of monocytic cells in systemic lupus erythematosus (SLE) patients, this study isolated and cultured peripheral blood monocytes from patients and healthy donors.

METHODS

Monocytes were isolated by gradient centrifugation and adherence to plastic dishes. The cells were then cultured for three days, partially supplemented with GM-CSF and interleukin 4 (IL4) to obtain dendritic cells. The differentiation status was monitored by the expression of surface markers using flow cytometry and cytokine secretion.

RESULTS

Monocytes from SLE patients expressed significantly lower numbers of the monocytic marker CD14 and HLA-DR while secreting significantly more tumour necrosis factor alpha (TNFalpha) than monocytes from healthy donors. The addition of GM-CSF and IL4 resulted in an inhibition of TNFalpha secretion, but was not sufficient to generate monocytederived dendritic cells.

CONCLUSION

Monocytes from SLE patients are severely altered in phenotype and function and have a limited differentiation flexibility towards the accessory type of monocytic cells.

[Erythrocyturia in pregnancy]

142 cases of erythrocyturia in the prepartal period were reexamined 3 months post partum. 15.5% of those examined already showed pyelonephritic changes in the uriograph and 57.6% had a corresponding anamnesis. Erythrocyturia was present in only 24.6% of cases 3 months post partum and in 12.5% of cases after 3 years. After 3 years there were no pathological urine findings in 70.8%. Because kidney punction gives rise to histological changes which are hard to detect and present an unacceptable risk, it is only indicated if the condition is observed over a long period--at least 2 years--and other procedures of nephrological examination have been exhausted. In a few cases it will already be necessary within the first year, with due attention given to therapeutic consequences. Equivalents of infection of the urinary passage and glomerular lesions should be treated and observed at a special kidney clinic over a period of years.